In modern lighting systems, lighting modules may comprise a programmable controller which controls the operation of the lighting module. This operation comprises, for example, the controlling of the light emission of a light source of the lighting module. The lighting modules with the programmable controller may be connected to a network and they may receive an update of the program that is executed by the programmable controller.
Published patent application US2007/0268151A1 relates to such a lighting system and discloses a method of programming a lighting device. The method is used to program an operation of a lighting device that comprises a light source. The lighting device comprises firmware and an interface for receiving external control commands for operating the light source. This method includes at least partially programming the firmware of the operating device or the interface by transmitting additional information to the interface.
In the above cited patent application it is suggested that the new firmware may be transmitted without interrupting the normal operation of the lighting device. In practical embodiments, the installation of the new firmware cannot be done while the lighting device is fully operational. Today, lighting devices are switched towards an upgrading operational mode in which the light sources are often switched off. Switching off the light sources is very inconvenient in many situations and in specific situations even undesirable when a minimum lighting level must be guaranteed. For example, in a road tunnel it is undesirable that during normal operation of the road tunnel the light sources are switched off for installing new software in the lighting modules.